title: Ethanol enhances carbachol-induced protease activation and accelerates Ca2+ waves in isolated rat pancreatic acini.
abstract: Alcohol abuse is a leading cause of pancreatitis, accounting for 30% of acute cases and 70-90% of chronic cases, yet the mechanisms leading to alcohol-associated pancreatic injury are unclear. An early and critical feature of pancreatitis is the aberrant signaling of Ca(2+) within the pancreatic acinar cell. An important conductor of this Ca(2+) is the basolaterally localized, intracellular Ca(2+) channel ryanodine receptor (RYR). In this study, we examined the effect of ethanol on mediating both pathologic intra-acinar protease activation, a precursor to pancreatitis, as well as RYR Ca(2+) signals. We hypothesized that ethanol sensitizes the acinar cell to protease activation by modulating RYR Ca(2+). Acinar cells were freshly isolated from rat, pretreated with ethanol, and stimulated with the muscarinic agonist carbachol (1 μM). Ethanol caused a doubling in the carbachol-induced activation of the proteases trypsin and chymotrypsin (p < 0.02). The RYR inhibitor dantrolene abrogated the enhancement of trypsin and chymotrypsin activity by ethanol (p < 0.005 for both proteases). Further, ethanol accelerated the speed of the apical to basolateral Ca(2+) wave from 9 to 18 μm/s (p < 0.0005; n = 18-22 cells/group); an increase in Ca(2+) wave speed was also observed with a change from physiologic concentrations of carbachol (1 μM) to a supraphysiologic concentration (1 mM) that leads to protease activation. Dantrolene abrogated the ethanol-induced acceleration of wave speed (p < 0.05; n = 10-16 cells/group). Our results suggest that the enhancement of pathologic protease activation by ethanol is dependent on the RYR and that a novel mechanism for this enhancement may involve RYR-mediated acceleration of Ca(2+) waves.
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: Abrahim I
authors.initials: AI
authors.lastname: Orabi
authors.forename: Ahsan U
authors.initials: AU
authors.lastname: Shah
authors.forename: Kamaldeen
authors.initials: K
authors.lastname: Muili
authors.forename: Yuhuan
authors.initials: Y
authors.lastname: Luo
authors.forename: Syeda Maham
authors.initials: SM
authors.lastname: Mahmood
authors.forename: Asim
authors.initials: A
authors.lastname: Ahmad
authors.forename: Anamika
authors.initials: A
authors.lastname: Reed
authors.forename: Sohail Z
authors.initials: SZ
authors.lastname: Husain
mesh_terms: D000437:Alcoholism / Q000503:physiopathology; D000818:Animals; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002217:Carbachol / Q000737:chemistry* / Q000494:pharmacology; D002918:Chymotrypsin / Q000737:chemistry; D003620:Dantrolene / Q000494:pharmacology; D004195:Disease Models, Animal; D000431:Ethanol / Q000494:pharmacology*; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D010179:Pancreas / Q000378:metabolism / Q000473:pathology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D015398:Signal Transduction; D014357:Trypsin / Q000737:chemistry
chemical_list: D009125:Muscle Relaxants, Central; D019837:Ryanodine Receptor Calcium Release Channel; D000431:Ethanol; D002217:Carbachol; D010447:Peptide Hydrolases; D002918:Chymotrypsin; D014357:Trypsin; D003620:Dantrolene; D002118:Calcium